Merged indexes are B-trees that contain multiple traditional indexes and interleave their records based on a common sort order. In relational databases, merged indexes implement “master-detail clustering” of related records, e.g., orders and order details. Thus, merged indexes shift de-normalization from the logical level of tables and rows to the physical level of indexes and records, which is...

Previous authors have shown how to build FM-indexes efficiently in external memory, but querying them efficiently remains an open problem. Searching näıvely for a pattern P requires Θ(|P |) random access. In this paper we show how, by storing a few small auxiliary tables, we can access data only in the order in which they appear on disk, which should be faster. An FM-index [4] is a compressed r...

To evaluate the clinical usefulness of measuring transthoracic electrical impedance in patients with pulmonary edema, we studied 27 normal subjects and 33 patients. In normal subjects, impedance increased when body position changed from supine to standing (p less than 0.01) and when lung volume increased from residual volume to total lung capacity (p less than 0.01). Impedance values vari7 omeg...

This report describes the results of a set of experiments conducted with AIMS (Assisted Indexing at Mississippi State), a system that aids human document analysts in the assignment of indexes to physical chemistry journal articles. We defined four different experiments using four different combinations of portions of an article (such as the title and the abstract) to determine which portions of...

The problem of indexing path queries in semistructured/XML databases has received considerable attention recently, and several proposals have advocated the use of structure indexes as supporting data structures for this problem. In this paper, we investigate efficient update algorithms for structure indexes. We study two kinds of updates — the addition of a subgraph, intended to represent the a...

We propose a new compression algorithm that is tailored to database applications It can be applied to a collection of records and is especially e ective for records with many low to medium cardinality elds and numeric elds In addition this new technique sup ports very fast decompression Promising application domains include decision sup port systems DSS since fact tables which are by far the la...

Search engines are an essential tool for modern life. We use them to discover new information on diverse topics and to locate a wide range of resources. The search process in all practical search engines is supported by an inverted index structure that stores all search terms and their locations within the searchable document collection. Inverted indexes are highly optimised, and significant wo...

The speciication and derivation of substitution for the de Bruijn representation of-terms is used to illustrate programming with a function-sequence monad. The resulting program is improved by interactive program transformation methods into an eecient implementation that uses primitive machine arithmetic. These transformations illustrate new techniques that assist the discovery of the arithmeti...